Missing Addends Made Easy

Friday, September 15, 2017

Missing addends are always a tricky concept for many students. I believe the cause of this is many reasons. Some students are still building their number sense, some students are simply careless, and some students don't truly understand that equal sign.

When a problem such as this is given to many students, they will simply see two numbers, add them, and write the answer in the blank.

You'll get this in return. Obviously, the 12 doesn't make sense when the problem is read back, but since most students at this age don't check over their work, they don't know to go back and rework it.

And, let's face it. Most of the time, students have been taught to look at the sign and put the answer in the blank. That's exactly what this student did. They think they've solved it correctly.

I've found something that works with my students. I call him THE EQUALIZER! (said in my best superhero voice)

First, when presented with a problem like this...

we talk about the equal sign and what it means. Many students will say it means "the answer" so this is something we clarify. We learn that equal means "the same" and we do a lot of demonstrations with manipulatives to show "the same."

Then, I introduce THE EQUALIZER who is a super hero with special powers - he makes everything "the same" or "fair." But, his super power is in his muscles and if his muscles aren't the same, his powers won't work.

So, we practice drawing his muscles. To do this, we always find the equal sign - his muscles grow from there. We draw a circle from one side of the equal sign, up and around the numbers, to the bottom of the equal sign and then repeat on the other side.

Once the muscles are drawn, students have to make sure they are "the same" so THE EQUALIZER will have his powers. In the illustration above, we see that one side is complete with a 10. So, we need to make the other side also equal 10. Drawing these "muscles" really lets students see the two sides of the equation.

This visual is just what many students need to be able to understand the problem and filll in the missing addend. However, a few students may still make careless errors. So, once the muscles are completed, the final step is to check.

I actually have my students label the muscles when checking to prove that the are equal. If they're not, the student knows they need to go back and try it again.

So, to review, these are the steps we use to "equalize" a problem.

When we're practicing this as a whole group, I let students who solve the problem correctly stand up on their chairs and flex their muscles for us! They've become EQUALIZERS!

They kind of eat it up. :) I hope this little tip helps your students master the tricky concept of missing addends!

3 comments

The Equalizer is awesome! What a great way to make that concept clear for your students. I like that it should even help them with what I consider to be the trickiest missing number equation: 3=_-10. My kiddos always want to write 7, but I bet the Equalizer will help them get it right this year! Thank you! :)

I'm also curious about your office dividers, privacy shields, or whatever you call them. Can you share what they are made from, and what they are displaying? They look terrific!

I love the Equalizer! They would be so proud--what do you do to instruct them for this concept. I teach special education and this is the most difficult concept for counting on or back. Also---please---so curious about your dividers or privacy shields, I am hoping they are in your store and what they are made from. They look like awesome student references!!!! I need those as a great tool.